Armoracia rusticana
 
Perennial root vegetable. Extremely hardy and tolerant of many soil and weather conditions. Perfect permaculture plant. 
 
Famed for its spicy, pungent root which is used to make a condiment much like wasabi. Many noted medicinal uses; as a GI stimulant, diuretic, vermifuge, etc.
 
Sold as a bare root piece with a growing tip.